Rapid detection of significant bacteria in the urine has been attempted with a variety of methods. The detection of adenosine triphosphate (ATP) in the urine was evaluated many years ago and found to be too non-specific for clinical application. Recent advances in spectrophotometer technology and reagent preparation have made it feasible to reevaluate this methodology. Our studies with over 500 urine specimens have suggested that this procedure may be useful for screening those urines to be further evaluated. However, a false negative rate of approximately 6% requires further study to try to develop media which will permit the detection of slow growing organisms such as yeast and nonfermenting gram negative bacilli. A false positive rate of approximately 12% also needs to be reduced so that unnecessary processing of urines is avoided. If this technique can result in accurate screening of urines in one hour, then it will reduce processing costs and decrease turnaround time.